Apparatus for enabling an autotrack circuit of an optical disc reading apparatus during the positioning of a read beam
Apparatus for enabling an autotrack circuit of an optical disc reading apparatus during the positioning of a read beam
Description
The invention relates to an apparatus for reading a disc-shaped record carrier in which information is stored in the form of a track of optically detectable areas, which apparatus comprises:
- means for rotating the carrier,
- a light source for producing a read beam,
- an objective system for focussing the read beam to form a read spot on the record carrier,
- a detection system for detecting the information present in the read beam after it has cooperated with the record carrier,
- radial positioning means for controlling the radial position of the read spot on the information track.
- a lock-in system for switching on the radial positioning means at an instant at which the light spot at least substantially coincides with the information track.
Such is for example a compact disc digital audio player, which at the time of filing of the present application is available from N.V. Philips’ Gloeilampenfabrieken under type number CD 303. In this player a selection to be reproduced can be keyed in before the disc is played. For this purpose use is made of the subcode which is interleaved with the digital audio information and which includes inter alia a running indication for the track number being reproduced, an index (part of a “track”), and relative and absolute time. Various known players can be programmed with respect to track number, Index and/or time. The keyed-in selection may be stored in a memory for the duration of the playing operation.
Patent : US4697258 – Apparatus for enabling an autotrack circuit of an optical disc reading apparatus during the positioning of a read beam
Octrooi : NL8403534A – Inrichting voor het uitlezen van een schijfvormige registratiedrager.
European Patent : EP0183303B1 – Apparatus for reading a disc-shaped record carrier.